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.\" $FreeBSD: releng/11.0/share/man/man9/intro.9 263142 2014-03-14 03:07:51Z eadler $
.\"
.Dd December 13, 1995
.Dt INTRO 9
.Os
.Sh NAME
.Nm intro
.Nd "introduction to system kernel interfaces"
.Sh DESCRIPTION
This section contains information about the interfaces and
subroutines in the kernel.
.Sh PROTOTYPES ANSI-C AND ALL THAT
Yes please.
.Pp
We would like all code to be fully prototyped.
.Pp
If your code compiles cleanly with
.Nm cc
.Ar -Wall
we would feel happy about it.
It is important to understand that this is not a question of just shutting up
.Nm cc ,
it is a question about avoiding the things it complains about.
To put it bluntly, do not hide the problem by casting and other
obfuscating practices, solve the problem.
.Sh INDENTATION AND STYLE
Believe it or not, there actually exists a guide for indentation and style.
It is not generally applied though.
.Pp
We would appreciate if people would pay attention to it, and at least not
violate it blatantly.
.Pp
We do not mind it too badly if you have your own style, but please make
sure we can read it too.
.Pp
Please take time to read
.Xr style 9
for more information.
.Sh NAMING THINGS
Some general rules exist:
.Bl -enum
.It
If a function is meant as a debugging aid in DDB, it should be enclosed
in
.Bd -literal -offset indent
#ifdef DDB

#endif /* DDB */
.Ed
.Pp
And the name of the procedure should start with the prefix
.Li DDB_
to clearly identify the procedure as a debugger routine.
.El
.Sh SCOPE OF SYMBOLS
It is important to carefully consider the scope of symbols in the kernel.
The default is to make everything static, unless some reason requires
the opposite.
.Pp
There are several reasons for this policy,
the main one is that the kernel is one monolithic name-space,
and pollution is not a good idea here either.
.Pp
For device drivers and other modules that do not add new internal interfaces
to the kernel, the entire source should be in one file if possible.
That way all symbols can be made static.
.Pp
If for some reason a module is split over multiple source files, then try
to split the module along some major fault-line and consider using the
number of global symbols as your guide.
The fewer the better.
.Sh SEE ALSO
.Xr style 9
.Sh HISTORY
The
.Nm
section manual page appeared in
.Fx 2.2 .